1. Field of the Invention
The present invention relates to a liquid ejection head having an ejection energy generating element that generates and applies energy to a liquid to eject the liquid through an ejection port, as well as a method for manufacturing such a liquid ejection head.
2. Description of the Related Art
Printing apparatuses using a liquid ejection head to eject droplets intrinsically eject droplets onto a print medium such as paper in a non-contact manner to attach the droplets to the print medium for printing. However, recent printing apparatuses using a liquid ejection head have more frequently been applied to print media other than paper. These printing apparatus have been used for printing on fibers, that is, textile printing, printing of circuits for manufacturing electric circuits, printing on glass substrates, or the like. For these printing apparatuses, one of a major factor affecting the quality of output images printed on print media is the landing accuracy of droplets. When the printing apparatus is used to print circuits in manufacturing electric circuits, the landing accuracy also affects the accuracy of the electric circuits. Thus, the landing accuracy of droplets from the liquid ejection head is an element determining the performance of the printing apparatus.
To allow the liquid ejection head to eject a liquid, an ejection energy generating element provided in the liquid ejection head needs to be energized. The liquid ejection head further has a connection portion that electrically connects wiring formed in a supporting member to the ejection energy generating element.
In general, the connection portion is desirably formed in position retracted from an ejection port formation face of the liquid ejection head on which an ejection port is formed, with respect to a direction in which droplets are ejected. If any area of the liquid ejection head projects from the ejection port formation face in the droplet ejecting direction, the projection correspondingly prevents the ejection port formation face of the liquid ejection head from being located closer to the print medium. Thus, to design a printing apparatus using a liquid ejection head having a portion projecting from the ejection port formation face in the ejection direction, it is necessary to design the apparatus taking into account the distance by which the projecting portion of the liquid ejection head projects from the ejection port formation face. This increases the distance between the ejection port formation face of the liquid ejection head and the print medium. The increased distance between the ejection port formation face of the liquid ejection head and the print medium may reduce the landing accuracy of ejected droplets. This may in turn degrade the quality of output images.
If the printing apparatus is designed such that the liquid ejection head are located very close to the print medium, in order to maintain the appropriate landing accuracy, then when for example, slight cockling occurs on the print medium, the projecting portion of the liquid ejection head may contact the print medium. In such a case, a surface of the print medium may be damaged, also degrading the quality of output images. If the liquid ejection head is used to print circuits in manufacturing electric circuits, the degraded quality of output images may affect the electrical characteristics of the electric circuits.
Japanese Patent Laid-Open No. 2004-237528 discloses a liquid ejection head having a connection portion which electrically connects a supporting member and an ejection energy generating element, and which has a reduced height. In the liquid ejection head disclosed in Japanese Patent Laid-Open No. 2004-237528, edge lines of a substrate is chamfered to prevent the wiring from contacting the substrate. This makes it possible to provide the liquid ejection head in which the connection portion is located farther than the ejection port formation face. In the liquid ejection head disclosed in Japanese Patent Laid-Open No. 2004-237528, the connection portion is located lower to reduce the size of the portion of the liquid ejection head which projects from the ejection port formation face. The smaller projecting portion reduces the distance between the ejection port formation face of the liquid ejection head and the print medium. This improves the landing accuracy of a liquid ejected from the liquid ejection head.
However, when the electric connection between the supporting member and the ejection energy generating element is established according to such a method as proposed in Japanese Patent Laid-Open No. 2004-237528, the wiring is located as the wiring is laid across between the supporting member and an element substrate at the connection portion. Consequently, the wiring at the connection portion functions as wiring allowing electricity to pass through while supporting the own weight. The wiring thus needs to have a sufficient strength to support the own weight. To have an increased strength, the wiring needs to be formed to be thicker. The wiring thus becomes thicker in the ejection direction, causing the connection portion of the liquid ejection head to project correspondingly in the liquid ejection direction. This increases the size of the portion of the liquid ejection head which projects from the ejection port formation face in the ejection direction. The liquid ejection head may thus be prevented from lying closer to the print medium, increasing the distance between the liquid ejection head and the print medium. The increased distance between the liquid ejection head and the print medium correspondingly reduces the landing accuracy of ejected droplets.